Expose a method in VariationsService to trigger a seed fetch.

chrome/browser/metrics/variations/variations_request_scheduler.h

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_METRICS_VARIATIONS_VARIATIONS_REQUEST_SCHEDULER_H_
 #define CHROME_BROWSER_METRICS_VARIATIONS_VARIATIONS_REQUEST_SCHEDULER_H_
 
 #include "base/bind.h"
 #include "base/gtest_prod_util.h"
 #include "base/time/time.h"
 #include "base/timer/timer.h"
 
 class PrefService;
 
 namespace chrome_variations {
 
 // A helper class that makes VariationsService requests at the correct times.
 class VariationsRequestScheduler {
  public:
   virtual ~VariationsRequestScheduler();
 
-  // Starts the task on a schedule.
+  // Starts the task. This can be a repeated event or a one-off.
   virtual void Start();
 
   // Resets the scheduler if it is currently on a timer.
   virtual void Reset();
 
   // Schedules a fetch shortly, for example to re-try the initial request which
   // may have failed.
-  void ScheduleFetchShortly();
+  void ForceFetch();
+
+  // Potentially fetch a new seed, depending on implementation. This may only
+  // fetch if there has not been one recently.
+  virtual void ScheduleFetch();
 
   // Factory method for this class.
   static VariationsRequestScheduler* Create(const base::Closure& task,
                                             PrefService* local_state);
 
  protected:
   // |task| is the closure to call when the scheduler deems ready.
   explicit VariationsRequestScheduler(const base::Closure& task);
 
   // Getter for derived classes.
   base::Closure task() const;
 
  private:
   FRIEND_TEST_ALL_PREFIXES(VariationsRequestSchedulerTest,
-                           ScheduleFetchShortly);
+                           ForceFetch);
 
   // The task scheduled by this class.
   base::Closure task_;
 
   // The timer used to repeatedly ping the server. Keep this as an instance
   // member so if VariationsRequestScheduler goes out of scope, the timer is
   // automatically canceled.
   base::RepeatingTimer<VariationsRequestScheduler> timer_;
 
   // A one-shot timer used for scheduling out-of-band fetches.
   base::OneShotTimer<VariationsRequestScheduler> one_shot_timer_;
 
   DISALLOW_COPY_AND_ASSIGN(VariationsRequestScheduler);
 };
 
 }  // namespace chrome_variations
 
 #endif  // CHROME_BROWSER_METRICS_VARIATIONS_VARIATIONS_REQUEST_SCHEDULER_H_